Relativistic and NonRelativistic Gas Flows in Astrophysical Media: the General Symmetric Solution in the Low Pressure Limit
Abstract
The dynamical expansion and motion of supernova remnants, double radio galaxies, etc., into and through the surrounding interstellar and/or intergalactic gas are processes of some importance in astrophysics for inferring energy, magnetic fields, particle pressure, etc. in a wide variety of astrophysical situations. We are usually hampered by the fact that it is often difficult to obtain a solution to the equations describing the flow of a gas into a surrounding medium starting from a postulated equation of state. The present paper shows how, by starting with a fluid flow that one believes adequately describes the gas, it is possible to solveby quadratures for the associated pressure and density. And in making these remarks we are implicitly assuming plane, cylindrical or spherically symmetric flow velocities which may be unsteady in time. The fluid speed can be chosen to be either nonrelativistic or relativistic, but the method is valid only when the resulting gas pressurep, is small compared to ϱc ^{2}, where ϱ is the mass density. We illustrate the method by solving a simple problem. In view of the ever increasing number of astrophysical situations where some measure of the fluid flow through an object is becoming available (often from Doppler shifted lines) we believe the present technique shou'd be of some use in helping to unravel the internal dynamical properties of the flowing gas.
 Publication:

Astrophysics and Space Science
 Pub Date:
 December 1976
 DOI:
 10.1007/BF00642668
 Bibcode:
 1976Ap&SS..45..327L
 Keywords:

 Astrodynamics;
 Flow Velocity;
 Gas Flow;
 Low Pressure;
 Nonrelativistic Mechanics;
 Relativistic Velocity;
 Conservation Equations;
 Flow Stability;
 Gas Density;
 Gas Pressure;
 Magnetic Fields;
 Quadratures;
 Astrophysics